Reproduction can occur at the cellular or organismal level. In cellular reproduction the original cell divides, producing two identical daughter cells that may then be used for body growth or repair. Reproduction of the human organism, or making a whole new person, is the major task of the reproductive system. When a sperm unites with an egg, a fertilized egg forms, which then develops into a baby within the mother’s body. The reproductive system is directly responsible for producing offspring, but its function is exquisitely regulated by hormones of the endocrine system.
Because males produce sperm and females produce eggs (ova), there is a division of labor in the reproductive process, and the reproductive organs of males and females are different (see Figure 1.3). Additionally, the female’s reproductive structures provide the site for fertilization of eggs by sperm, then protect and nurture the developing fetus until birth.